WEST PALM BEACH, Fla. — Kristy Bryner worries her 80-year-old mom might slip and fall when she picks up the newspaper, or that she'll get in an accident when she drives to the grocery store. What if she has a medical emergency and no one's there to help? What happens if, like her father, her mother slips into a fog of dementia? Those questions would be hard enough if Bryner's aging parent lived across town in Portland, Ore., but she is in Kent, Ohio. The stress of caregiving seems magnified by each of the more than 2,000 miles that separate them. "I feel like I'm being split in half between coasts," said Bryner, 54. "I wish I knew what to do, but I don't." As lifespans lengthen and the number of seniors increases, more Americans find themselves in Bryner's perilous position, struggling to care for an ailing loved one from hundreds or thousands of miles away. The National Institute on Aging estimates around 7 million Americans are long-distance caregivers. Aside from economic factors that often drive people far from their hometowns, shifting demographics in the country could exacerbate the issue: Over the next four decades, the share of people 65 and older is expected to rapidly expand while the number of people under 20 will roughly hold steady. That means there will be a far smaller share of people between 20 and 64, the age group that most often is faced with caregiving. By Matt Sedensky